MANILA, Philippines—President Macapagal-Arroyo can never be prime minister, Sen. Joker Arroyo said Thursday.

"She is now very weak. She has no political clout; what more if she is only a congresswoman?" asked Arroyo at a press conference in the Senate.

"She can never be prime minister because we have to amend first the Constitution. Since she cannot amend it, no way. For all you know, she is laughing inside her," said Arroyo.

The senator said that the choice of the next speaker of the House of Representatives was a prerogative of the incoming President.

How can she succeed as speaker—she cannot do that—because the speaker of the next House will be the choice of whoever is the President," said Arroyo, pointing out that former President Cory Aquino's speaker was the late Ramon Mitra, former President Fidel Ramos had Jose De Venecia, former President Joseph Estrada had Manny Villar and President Arroyo had De Venecia.

"So the speaker will be choice of the President. Let us forget this speculation. Chances are there will be no President that will support that—Noynoy won't, Villar won't, Erap won't and even Teodoro won't," he said, referring to presidential candidates Benigno Aquino, Villar, Joseph Estrada and Gilbert Teodoro.

"Let's forget talk about she running... the House—that can never happen," said Arroyo.

The senator, however, said that nobody can stop Ms Arroyo from running for Congress.

But as to the fear that Ms Arroyo would work to amend the Constitution so could become prime minister, he said: "The road is long. One thing we can be sure of is this President Arroyo as President has made many attempts to amend the Constitution (but) failed."

"So what’s the point? The Constitution cannot be amended simply because she will run for Congress. As President she failed."

On Executive Secretary Eduardo Ermita's admission that Cha-cha was on top of Ms Arroyo's agenda in seeking a congressional post, Arroyo said that even Ermita admitted that "he cannot read the mind of the President."